Method for the Production of a Circuit Board Involving the Removal of a Subregion thereof, and Use of such a Method

Abstract

The invention relates to a method for producing a circuit board involving the removal of a subregion thereof. In said method, at least two layers or plies of the circuit board ( 1 ) are interconnected, the subregion ( 6 ) to be removed is prevented from being connected to an adjacent ply of the circuit board by providing a layer ( 7 ) of adhesion-preventing or bonding-preventing material, and peripheral zones ( 8 ) of the subregion ( 6 ) to be removed are separated from adjoining zones of the circuit board ( 1 ). According to the invention, a fissure formation and/or a detachment from the subregion ( 6 ) of the circuit board ( 1 ) to be removed is initiated in a subregion in or on the layer ( 7 ) of adhesion-preventing or bonding-preventing material, and the subregion ( 6 ) to be removed is then removed, thus making it possible to remove a subregion ( 6 ) to be removed from a circuit board ( 1 ) in a simple and reliable, and if necessary automated, manner. Also disclosed is a use of such a method for producing a multilayer circuit board ( 1 ) and especially for creating voids in such a circuit board ( 1 ).

1 . A method for the production of a circuit board involving the removal of a subregion thereof, wherein at least two layers or plies of the circuit board are interconnected, and the subregion to be removed is prevented from being connected to an adjacent ply of the circuit board by providing a layer made of an adhesion-preventing or bonding-preventing material, and edge regions of the subregion to be removed are separated from adjoining regions of the circuit board, characterised in that, a crack formation and/or a detachment from the subregion of the circuit board to be removed is induced in an edge region in or on the layer made of the adhesion-preventing or bonding-preventing material and the subregion to be removed is then removed. 
     
     
         2 . The method according to  claim 1 , characterised in that one of the crack formation and detachment from the subregion of the circuit board to be removed in or on the layer made of the adhesion-preventing material is produced by an introduction or forming of twists of the subregion to be removed, said twists being produced as a result of a non-uniform stressing of said subregion to be removed. 
     
     
         3 . The method according to  claim 2 , characterised in that the non-uniform stresses are introduced onto the subregion to be removed as the subregion to be removed is separated from regions of the circuit board adjoining said subregion to be removed. 
     
     
         4 . The method according to  claim 1 , characterised in that the edge regions of the subregion to be removed are defined and/or separated or severed in a manner known per se by a milling, carving or cutting, in particular laser cutting. 
     
     
         5 . The method according to  claim 1 , characterised in that a crack formation is induced by introducing an increased mechanical stress or increased energy when the edge regions of the subregion to be removed are severed from regions of the circuit board adjoining said subregion to be removed. 
     
     
         6 . The method according to  claim 5 , characterised in that a laser cutting process with introduction of increased energy is performed at least at one edge region of the subregion to be removed. 
     
     
         7 . The method according to  claim 6 , characterised in that the increased energy is introduced by an oscillating laser beam. 
     
     
         8 . The method according to  claim 1 , characterised in that, to induce a crack formation, heat energy is fed in at one point in a substantially central region following the separation of the edge regions of the subregion to be removed from adjoining regions of the circuit board to be removed. 
     
     
         9 . The method according to  claim 1 , characterised in that the adhesion-preventing or bonding-preventing material is formed in a manner known per se by a waxy paste, which, during a process in which at least two layers or plies of the circuit board are connected, prevents an adhesion or bonding between the subregion to be removed subsequently and the adjacent ply of the circuit board. 
     
     
         10 . The method according to  claim 9 , characterised in that the waxy paste is mixed with a propellant, which is released following a connection of at least two layers or plies of the circuit board with exposure of the subregion to be removed to a temperature that is increased compared with a temperature during the production of the connection between the layers or plies of the circuit board. 
     
     
         11 . The method according to  claim 10 , characterised in that the separation or severing of edge regions of the subregion to be removed from regions of the circuit board adjoining said subregion to be removed is performed after the release of the propellant. 
     
     
         12 . The method according to  claim 10 , characterised in that the propellant is formed by azodicarbonamide, p-toluenesulfonyl semicarbazide or 5-phenyltetrazole. 
     
     
         13 . The method according to  claim 1 , characterised in that the subregion to be removed is removed from the circuit board using an aid adhering temporarily to said subregion to be removed, for example an adhesive tape or the like. 
     
     
         14 . The method according to  claim 1 , characterised in that the subregion to be removed is removed in an automated manner. 
     
     
         15 . The method according to  claim 13 , characterised in that a plurality of subregions to be removed are removed substantially simultaneously, in particular from a plurality of circuit boards, with use of a common aid. 
     
     
         16 . Use of a method according to  claim 1  for the production of at least one channel in a circuit board. 
     
     
         17 . The use according to  claim 16  for the revealing of at least one element, in particular a recording element, in the interior or in inner plies of a multi-ply circuit board. 
     
     
         18 . The use according to  claim 16  for the production of recessed and/or stepped subregions of a circuit board. 
     
     
         19 . The use according to  claim 16  for the production of a rigid/flexible circuit board.